Infinite speed control for automatic washer

ABSTRACT

A VARIABLE SPEED DRIVE MEANS IS PROVIDED FOR AN AUTOMATIC WASHER HAVING A ROTATABLE CONTAINER, AN AGITATION MEANS MOUNTED IN THE CONTAINER, AND TRANSMISSION AND CONTAINER FOR WASHING FABRICS AND CENRIFUGALLY EXTRACTING FLUID FROM THE FABRICS. THE IMPROVEMENT COMPRISES A WOUND ROTOR MOTOR CONNECTED TO THE TRANSMISSION MEANS TO PROVIDE ROTOR MOTOR CONNECTED TO THE TRANSMISSION THE ELECTRICAL IMPEDANCE IN SERIES WITH THE ROTOR WINDINGS OF THE MOTOR, AND ENERGY DISSIPATION MEANS ADAPTED TO REMOVE ENERGY BY FRICTION DURING CENTRIFUGAL EXTRACTION. BY VARYING THE ELECTRICAL IMPEDANCE, A SUBSTANTIAL VARIATION IN MOTOR SPEED IS ACHIEVED.

INFINITE SPEED CONTROL FOR AUTOMATIC WASHER Filed April 24, 1969 J. C. WORST March 16, 1971 2 Sheets-Sheet 1 T Y 0 Z II E O 2 S 5 WW m I T c //6 T .21 A n 0 o o .0 o 0 M w s o o o o o 4 E M o o o 0 Z 5 M M m 0 o o O O A I v O o o o 3 OJ V. \1 5 o M o o 1 5 2 B m s o o 3 I 3 7 2 z I a 1 01 I 4 G I 0 II! I 3 a o o o 7 8 3 a a F o o O 2 2 9,; 6 h 3 H H \l o o o o M #1 Z 0 o fl 0 o 4 3 6 o o 4 4 u H 3 F 6 8 B 0 w 5 E I Z I v a I G A: h 1. l\\ I a a I 2 I 3 j I e /2 r4 2 /o March 16, 1971 INFINITE SPEED CONTROL FOR AUTOMATTC WASHER MOTOR SPEED m RPM Filed April 24, 1969 J. C. WORST 2 Sheets-Sheet 2 l I 20 3o 40 TORQUE m OuNcE-FEET PIC-3.3

INVENTOR. IOSEPH C. WORST 0 H \s ATTORNEY United States Patent 3,570,274 INFINITE SPEED CONTROL FOR AUTOMATIC WASHER Joseph C. Worst, Louisville, Ky., assignor to General Electric Company Filed Apr. 24, 1969, Ser. No. 818,918 Int. Cl. D06f 29/00 US. Cl. 68-2337 9 Claims ABSTRACT OF THE DISCLOSURE A variable speed drive means is provided for an automatic Washer having a rotatable container, an agitation means mounted in the container, and a transmission means adapted to selectively drive the agitation means and container for Washing fabrics and centrifugally extracting fluid from the fabrics. The improvement comprises a wound rotor motor connected to the transmission means to provide power thereto, a control means to vary the electrical impedance in series with the rotor windings of the motor, and energy dissipation means adapted to remove energy by friction during centrifugal extraction. By varying the electrical impedance, a substantial variation in motor speed is achieved.

BACKGROUND OF THE INVENTION This invention relates generally to a variable speed drive means for an automatic washer.

It is desirable in automatic clothes washers to provide a means of varying the speed of the washer over a Wide range, both during agitation and during centrifugal extraction. A variety of devices have been proposed to effect this feature, but most such devices comprise expensive and intricate additions to the domestic clothes washer.

It is therefore an object of my invention to provide an extremely simple and inexpensive means for varying the speed of an automatic washer over a wide range both during agitation and during centrifugal extraction.

SUMMARY OF THE INVENTION Briefly stated, in accordance with one aspect of the present invention, there is provided a variable speed drive means for a washing machine having a rotatable container adapted to receive fluid and fabrics to be washed in the fluid, agitation means mounted in the container to effect washing of the fabrics, and a transmission means adapted to selectively drive the agitation means and container for washing fabrics and centrifugally extracting fluid from the fabrics. The improvement comprises a wound rotor motor connected to the transmission means to provide power thereto, a control means to vary the electrical impedance in series with the rotor windings of said motor, and an energy dissipation means adapted to remove energy by friction during centrifugal extraction thereby providing a drag on said motor which is proportional to the speed thereof. By varying the electrical impedance, a substantial variation in motor speed is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention will be better understood from the following description of the preferred embodiment taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevatioal view of a clothes washing machine of the type which may suitably include my invention, the view being partly broken away and partially in section to illustrate details.

FIG. 2 is a schematic diagram of an electric circuit illustrating various details of my invention; and

3,570,274 Patented Mar. 16, 1971 FIG. 3 is a graphical illustration of motor speed vs. torque wherein various characteristics showing the results of my invention are represented.

DESCRIPTION OF THE PREFERRED EMBODIMENT imperforate tub or casing 13 which serves as a liquid receptacle. The basket 11 may be provided with a suitable clothes retaining member 14 for preventing the clothes from being floated over the top of the basket, and with a balance ring 15 to held steady the basket when it is rotated at high speed.

Tub 13 is rigidly mounted within an outer cabinet 16 which includes a cover 17 hingedly mounted in the top portion 18 of the cabinet for providing access through an opening 19 to the basket 11. A gasket 20 may be provided to form a seal between the top of tub 13 and the top portion 18 of the cabinet, thereby preventing the escape of moisture and moist air into the cabinet around the tub. The rigid mounting of tub 13 within cabinet 16 may be effected by any suitable means. As a typical example of one such means I provide strap members 21, each of which is secured at one end to an inturned flange 22 of the cabinet and at its other end to the outside of tub 13. At the center of basket 11 there is positioned a vertical axis agitator 23 which includes a center post 24 and a plurality of curved water circulating Water vanes 25 joined at their lower ends by an outwardly flared skirt 26.

Both the clothes basket 11 and the agitator 26 are rotatably mounted. The basket is mounted on a flange 27 of a rotatable hub 28, and the agitator 23 is mounted on a shaft (not shown) which extends upwardly through the hub 28, through the center post 24 and is secured to the agitator so as to drive it. During the cycle of operation of machine 10 water is introduced into the tub 13 and basket 11, and the agitator 23 is then oscillated back and fourth on its axis within the basket to wash the clothes therein. Then, after a predetermined period of this washing action, basket 11 is rotated at high speed to centrifugally extract the washing liquid from the clothes and discharge it to drain. Following this extraction operation, a supply of clean liquid is introduced into the basket for rinsing the clothes and the agitator is again oscillated. Finally, the basket is once more rotated at high speed to extract the rinse water.

A transmission means 29 is disposed beneath basket 11 and agitator 23 and is adapted to support and selectively drive the agitator 23 and basket 11 for washing fabrics and for centrifugally extracting fluid therefrom. A reversible motor 30 provides power to transmission 29 through a clutch 31 mounted on the motor shaft and through a suitable belt 32. Depending on the direction of motor rotation, pulley 33 of transmission means 29 is driven in opposite directions. When motor 30 is rotated in one direction, the transmission causes agitator 23 to oscillate in a substantially horizontal plane within the basket 11. Conversely, when the motor 30 is driven in the opposite direction, the transmission rotates the basket 11 and the agitator 23 together at high speed for centrifugal liquid extraction.

While this specific type of transmission mechanism used does not form a part of the invention, reference is made to US. Pat. No. 2,844,l225 issued July 22, 1958 to Mr. James R. Hubbard et al. and assigned to the assignee of the present invention. That patent discloses in detail a transmission mechanism which, without change in gearing or other essential drive detail, is suitable for use in the illustrated machine. In particular, the Hubbard et al. patent teaches the use of a transmission means having a casing 34 and a gear frame 35 disposed therein, the gear frame 35 being keyed to the basket 11 for rotation therewith. As will be explained later in greater detail, the instant invention may provide a modification in the peripheral design of gear frame 34 so as to provide a means of dissipating energy by viscous friction within transmission 29. However, such modification, as previously mentioned, does not change the gearing or other drive detail as disclosed by the Hubbard et al. patent.

Of course, when motor 30 starts rotating in the direction to cause high speed rotation of basket 11 and agitator 23, a very substantial load requirement is placed on the motor in order to accelerate the basket up to full speed. In order to permit the use of a relatively light motor, which is completely suitable at all other times, without burning it out during basket acceleration, clutch 31 is built to provide slippage between motor 30 and transmission 29 during times when the torque requirements on the motor would otherwise be excessive. As a result, when the motor 30 starts to rotate in the direction causing spinning of the basket 11, the slippage within clutch 31 causes a slow acceleration of basket 11, so that there is an appreciable amount of time (for instance on the order of 120 seconds) before the basket is fully up to speed; also, there is a substantial amount of time (for instance 60 seconds) during which the peed of the basket is substantially below that at which any substantial compressive forces are exerted on the clothes. It will be understood that there are many clutches which are well known in the art and may be designed to fulfill this function, and therefore the internal structure of clutch 31 is not further discussed herein.

In addition to operating transmission 29, as described, motor 30 also provides a direct drive through a flexible coupling 36 to a pump structure, generally indicated by the numeral 37, which may include two separate pumping units 38 and 39 both operated simultaneously in the same direction. Pump unit 38 has an inlet 40 which is connected by a conduit 41 to an opening 42 formed at the lowermost point of tub 13. Pump unit 38 also has an outlet 43 which is connected by a conduit 32 to a suitable drain (not shown). Pump unit 39 has an inlet connected by a conduit 44 to the interior of tub 13 and an outlet connected by a conduit 45 to a nozzle 46. The pump units are formed so that in the spin direction of motor rotation, pump unit 38 will draw in liquid from the opening 42 through conduit 41 and then discharge it through outlet opening 43 to drain, and, in the other direction of rotation, pump 39 will draw in liquid through conduit 44 and discharge it through conduit 45 and nozzle 46, each of the pump units being substantially inoperative in the direction of rotation in which it is not used.

Nozzle 46 is positioned to discharge into a filter pan 47 secured on the top portion 48 of agitator 23 so as to be movable therewith. By this structure, when motor 30 is rotating to provide agitation, pump unit 39 draws liquid through conduit 44 from tub 13 and discharges into conduit 45 such that liquid passes from nozzle 46 into filter pan 47 and then down through a number of small openings 49 provided in the bottom of the filter pan 47 and back into basket 11. In this manner, the filter pan 47 with its small openings 49 and its upstanding sidewall 50 causes much of the lint which is separated from the clothes during the Washing operation to be filtered out of the water, and thus prevents it from being redeposited on the clothes.

The motor 30, clutch 31, transmission means 29, basket 11 and agitator 23 form a suspended washing and centrifuging system which is supported by the stationary structure of the machine so as to permit oscillation of vibration from the stationary structure. It will be understood that such vibrations occur primarily as a result of high speed spinning of basket 11 and the load of fabrics therein as mentioned above. While any suitable suspension structure may be used, one such structure includes a bracket member 51 with transmission means 29 mounted on the top thereof and motor 30 mounted on the other side thereof. The bracket member 51 is in turn secured to upwardly extending rigid members 52, and each of the members 52 is connected to a cable 53 supported from the top of the machine. While only a portion of the vibration isolating system is shown in the drawings, such a vibration isolating system is fully described and claimed in U.S. Pat. No. 2,987,190 issued June 6, 1961 to Mr. John Bochan and assigned to the assignee of the present invention.

In order to accommodate the movement which occurs between basket 11 and tub 13 without danger of leakage between them, the statinary tub 13 is joined to the upper part of transmission means 29 by a flexible member 54. A member of this type is described and claimed in U.S. Pat. 2,959,966 issued Nov. 15, 1960 to Mr. John Bochan and assigned to the assignee of the present invention.

Hot and cold water may be supplied to the machine through conduits 55 and 56 which are adapted to be connected respectively to sources of hot and cold water (not shown). Conduits 55 and 56 extend into a conventional mixed valve structure 57 having solenoids 58 and 59. Hose 60 connects with an inlet nozzle 61 adapted to direct water into basket 11. In a conventional manner, selective or concurrent energization of solenoids 58 and 59 will provide for the passage of hot, cold or warm water from the mixing valve 57 through the inlet nozzle 61. When one or both of solenoids 58 and 59 are energized, water discharges from the inlet nozzle 61 and enters basket 11 and tub '13.

The level to which water rises in the basket and tub may be controlled by any suitable liquid level sensing means. One typical arrangement for doing this is to provide an opening 6 2 in the side of tube 13 adjacent to the bottom thereof, the opening 62 being connected through a conduit 63 and a tube 64 to a conventional pressure sensitive device (not shown) which may be positioned within the backsplash 65 of the machine 10. In the conventional manner, as the water rises within basket 11 and tub 13 it exerts increasing pressure on the column of air trapped in tube 64 and, at a predetermined pressure level, the column of air then trips the pressure sensitive device to shut off whichever of solenoids 58 and 59 may be energized. The backsplash 65 may have suitable manual controls, such as that shown at 66, extending therefrom so that the particular type of cycle, including for instance washing and spin speeds, water temperatures, water levels within tub 13 and basket 11, etc., may be controlled to effect the washing of different types of fabrics.

It will be understood that, while the description of the machine thus far excludes a substantial amount of detail relating to the drive, and does not show all of the valves and particular controls normally provided on modern domestic washing machines, the elimination and simplification of these items is primarily for the purpose of permitting a clear explanation of the inventive concept set forth below. It will be recognized that the omitted details are conventional items included in virtually all domestic washing machines, whose structure and positioning is well known to those skilled in the art.

In accordance with the present invention, means are provided to vary the speed of machine 10' during both agitation and centrifugal extraction. An essential feature of my invention is the utilization of a wound rotor motor as the drive motor 30, and the provision of control means to vary the electrical impedance in series with the rotor windings of motor 30. Further, an energy dissipation means adapted to remove energy by friction during centrifugal extraction is included to provide a drag on the motor 30 which is proportional to the speed thereof. By this arrangement, varying the electrical impedence in series with the rotor windings causes a substantial variation in the speed of the motor 30 and hence in the agitation and centrifugal speed of the washer 10.

Referring now to FIG. 2, a typical variable impedence system is shown connected in electrical series with the rotor windings of wound rotor motor 30. In particular, a first rotor winding 67 and a second rotor winding 68 are shown, each having one common end connection to lead 69. The other ends of windings 67 and 68 terminate in leads 78 and 71, respectively. Leads 69, 70 and 71 each connect with separate slip rings 72, 73 and 74, respectively, having separate brushes 75, 76 and 77, respectively associated therewith to provide stationary electrical contacts having connection to the rotor windings 67 and 68. Leads 78, 79 and 80" connecting respectively with brushes 75, 76 and 77 provide connection with a control means 81 comprising first and second variable impedence elements 82 and 83.

In the preferred embodiment of my invention, elements 82 and 83 comprise variable resistors having a common means of actuation in the form of knob 84. First varia'ble resistance 82 is connected in electrical series with first rotor winding 67, and second variable resistance 83 is connected in electrical series with second rotor winding 68. By simultaneously increasing the electrical resistances in series with the rotor windings, the speed of the motor may be decreased. However, the amount of motor speed decrease which is obtained by a predetermined increase of the resistances in series with the rotor windings, varies with the type of load being driven by the motor. This may be better understood by referring to FIG. 3 wherein three separate load lines 85, 86 and 87 are shown representing the motor speed vs. torque relationships for each of three types of motor loads, and wherein the intersections of these load lines with resistance curves R R R and R determine the amount of motor speed decrease corresponding to a specific resistance increase as a fraction of the particular motor load.

Turning initially to the load lines themselves, load line 85 represents the typical motor load of an automatic washer during agitation. Load line 86, however, represents the typical motor load of an automatic washer during centrifugal extraction. The obvious difference in slopes of these two load lines is accounted for by the differences between the agitation motor load and the centrifugal extraction motor load. In agitation, the motor 30 is required to oscillate agitator 23 back and forth within basket 11 wherein the fluid within basket 11 and tub 13 provides a viscous damping action or a viscous energy dissipation. Such viscous friction characteristically dissipates energy in proportion to the square of the speed of agitator 23 or motor 30 resulting in load line 85 having a smaller slope than load line 86 wherein no substantial energy is dissipated by viscous friction during centrifugal extraction.

With this understanding of the differences in loads represented by the load lines 85 and 86, it may now be seen how the amount of motor speed decrease may vary according to the type of load when a predetermined resistance increase is effected in series with the rotor wind ings. Curves R R R and R represent progressively higher resistances in series with the rotor windings. The intersection 88 of curve R and load line 85 may be seen to result in a motor speed of approximately 1675 r.p.m. Similarly the intersection 89 of curve R with load line 85 may be seen to result in a motor speed of approximately 1450* r.p.m. Hence, by increasing the resistances in series with the rotor windings from R to R a motor speed decrease of 1675 1450 225 r.p.m. will take place during agitation.

This result is to be compared, however, with the motor speed reduction achieved by the same resistance increase during centrifugal extraction, as represented by the intersections 90 and 91 of curves R and R with load line 86. It will be seen that here a motor speed reduction of only about l77S-l725=50 r.p.m. is effected.

Such an unequal motor speed decrease resulting from a corresponding resistance increase during agitation and centrifugal extraction renders this method of speed control ineffective for normal washer operation, since speed control is at least as equally important in centrifugal extraction as it is in agitation; and as seen above, such speed control during centrifugal extraction is effective over a much smaller range than during agitation. A resistance increase from R to R for instance, will produce approximately a 25% speed decrease during agitation, but only about an 8% speed decrease during centrifugal extraction.

To overcome this problem and to enable speed control during centrifugal extraction by the same FIG. 2 circuit as is effective to control agitation speed, I provide by my invention the inclusion of a dissipation means adapted to remove energy by friction during centrifugal extraction. Such a dissipation means thereby provides a drag on the motor 30 during centrifugal extraction, the drag being proportional to the motor speed. The effect of such energy dissipation means is to alter load line 86 to a new configuration which more closely resembles the agitation load line 85. Such an altered centrifugal extraction load line is shown at 87 on the graph of FIG. 3. Although the slope of load line 87 is shown as being greater than load line 85, such slope may be altered to be greater, less than, or equal to the slope of load line as desired by altering the structure and form of energy dissipation means used.

In the preferred embodiment, the energy dissipation means of my invention is incorporated within transmission means 29. Although energy dissipation by mechanical friction is possible in such an environment, it is more desirable to accomplish energy dissipation by viscous friction which results in an increase in load in proportion to the square of the motor speed.

In order to achieve such viscous energy dissipation within transmission means 29, the periphery of rotatable gear frame 35 is modified from that disclosed in the aforementioned Hubbard et al. patent, so as to provide a narrow arcuate space 92 between the circular side wall of housing or casing 34 and the periphery of gear frame 35, whereby the rotatable gear frame 35 may rotate in close proximity to the interior of housing or casing 34. Additionally one or more holes 93 are provided to allow the lubricating fluid employed to lubricate the gearing and drive mechanism of the transmission means to enter the space 92 as to provide viscous damping or energy dissipation. By this arrangement, lubrication fluid operates with in the narrow space 92 to provide a viscous dissipation of energy. As gear frame 35 rotates only during centrifugal extraction, the provision of a viscous energy dissipation means does not affect the agitation load line 85 and simply serves to modify the load line 86 to the configuration of load line 87, wherein a resistance increase from R to R will result in a motor speed reduction of approximately 17001500=200 r.p.m. as represented by curve intersections 94 and 95.

As was previously mentioned, my system is particularly adapted for use in automatic clothes washers wherein it is desirable to provide a means of varying the speed of a washer over a wide range both during agitation and during centrifugal extraction. From the foregoing description it should now be apparent that the present invention provides such a variable speed drive means by providing a wound rotor motor having a variable impedance in series with the rotor windings, and by providing an energy dissipation means effective during centrifugal extraction.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of the construction of the example illustrated, and it is contemplated that various other modifications, applications or variations will occur to those skilled in the art. It is therefore intended to cover such modifications,

applications and variations as do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a washing machine including a rotatable container adapted to receive fluid and fabrics to be washed in the fluid, agitation means mounted in the container to effect washing of the fabrics, and a transmission means to selectively drive the agitation means and container for washing fabrics and centrifugally extracting fluid from the fabrics; the improvement of a variable speed drive means comprising:

a wound rotor motor connected to the transmission means to provide power thereto;

control means to vary the electrical impedance in series with the rotor windings of said motor; and

energy dissipation means adapted to remove energy by friction during centrifugal extraction thereby providing a drag on said motor which is proportional to the speed thereof;

whereby varying said electrical impedance causes a substantialy variation in the speed of said motor during centrifugal extraction as well as during agitation.

2. The invention of claim 1 wherein said energy dissipation means is adapted to remove energy by viscous friction.

3. The invention of claim 2 wherein said energy dissipation means is incorporated within the transmission.

4. The invention of claim 3 wherein said energy dissipation means comprises:

a housing having a circular side wall and adapted to contain a quantity of lubricating fluid; and

rotatable means positioned 'within said housing and adapted to rotate in close proximity to the interior surface of said housing during centrifugal extraction; whereby said lubricating fluid operates within the narrow space between said side wall and said rotatable means to provide a viscous dissipation of energy.

5. The invention of claim 1 wherein said control means comprises a separate variable impedance in series with each of said rotor windings.

6. The invention of claim 1 wherein said control means comprises a separate variable resistance in series with each of said rotor windings.

7. The invention of claim 6 wherein;

said wound rotor motor includes a first rotor winding and a second rotor winding;

said control means comprises a first variable resistor,

a second variable resistor, and means adapted to simultaneously vary each of said variable resistors; and

said first variable resistor is connected in electrical series with said first rotor winding, and said second variable resistor is connected in electrical series with said second rotor winding.

8. In a washing machine including a rotatable container adapted to receive fluid and fabrics to be washed in the fluid, agitation means mounted in the container to effect Washing of the fabrics, and a transmission means to selectively drive the agitation means and container for washing fabric and centrifugally extracting fluid from the fabrics; the improvement of a variable speed drive means comprising:

a wound rotor motor connected to the transmission means to provide power thereto; said motor having at least two rotor windings;

control means comprising a separate variable resistor connected in electrical series with each of said rotor windings to vary the electrical resistance in series with each of said windings; and

energy dissipation means associated with the transmission and adapted to remove energy by viscous friction during centrifugal extraction;

whereby simultaneously varying each of said electrical resistance causes a substantial variation in the speed of said motor.

9. The invention of claim 8 wherein said energy dissipation means comprises:

a housing having a circular side wall and adapted to contain a quantity of lubricating fluid; and

rotatable means positioned within said housing and adapted to rotate in close proximity to the interior surface of said housing during centrifugal extraction;

whereby said lubricating fluid operates within the narrow space between said side wall and said rotatable means to provide a viscous dissipation of energy.

References Cited UNITED STATES PATENTS 2,946,409 7/1960 Jennings 188-134 3,018,649 1/1962 Barbulesco et a1 68-12 3,065,396 11/1962 Carlson 318-229 3,090,472 5/1963 Morrison 188-134X 3,152,463 10/1964 Sones et al. 68-12 3,301,023 1/1967 Painter 68-12 ROY D. FRAZIER, Primary Examiner J. F. FOSS, Assistant Examiner US. Cl. X.R. l8890; 318-229 

